Pinceladas gramaticales: main meanings of modal verbs

MODAL VERBS/MODALS

In my post today, I'll give you a practical summary of the main meanings expressed by the set of verbs generally called modal verbs or modals. 
Modals can express a varied range of ideas and shades of meaning, very useful to complete the English verb conjugation system.
They are usually divided into central modals (can/could, may/might, must, shall/should, will/would) and semi-modals or marginal modals (ought to, used to, need, dare). 
I'll concentrate on the main meanings expressed by the central modals, though I will include some notes about the following semi-modals: ought to, as an alternative to should, needn't (the negative of need), for absence of obligation, and used to, for habitual actions in the past, as against to be used to, for sth you are accustomed to doing.

1.- CAN/MAY?

· Can indicates mainly capacity or abilility to do sth:

I’m sure he can do (it) better than that – estoy seguro de que puede hacerlo mejor.

My wife can speak French - mi mujer sabe hablar francés.

 · May indicates that sth is possible:

It may rain this afternoon - puede que llueva esta tarde.

· Both can and may can be used to indicate ‘permission’, but may is more formal than can:

Can I smoke? - ¿puedo fumar? (informal)

May I smoke? - ¿puedo fumar? (formal)

Practice -1

 Fill in the gaps with can or may as required

a.- Gwen ........... play the piano, but she ............... play the violin.

b.- He says he ........... come this weekend if he ............... find a cheap flight.

c.- ................. you walk a bit faster? We’re going to be late for the concert.

d.- The TV said that it .................... be colder tomorrow.

e.- If there’s anything I .................... do to help you give me a ring.

f.- Mum, ................. I borrow your necklace for Linda’s wedding?

g.- Excuse me, Madam, .................... I use your phone?

KEY 1

a.- can; can’t; b.- may; can; c.- can; d.- may/might; e.- can; f.- can; g.- may.

2.- ‘PODER’ IN THE INFINITIVE AND FUTURE AND PERFECT TENSES

Can, like the rest of modals, is defective, lacking a to-infinitive and a participle, so to translate ‘poder’ in the infinitive, the future or perfect tenses use to be able:

I won’t be able to come tomorrow – no podré venir mañana.

I haven’t been able to do it – no he podido hacerlo.

Practice -2

Complete the sentences with the adequate form of to be able

a.- In fifty years’ time I’m sure that everybody ........... to live to a hundred.

b.- I have your report, but I ........................ to read it yet.

c.- I’ve always wanted ............................... to speak Japanese.

d.- Martin has just phoned to say that he ......................... to come tomorrow.

KEY 2

a.- will be able; b.- haven’t been able; c.- to be able; d- won’t be able

3.- MUST/SHOULD?

Both can mean ‘deber’, but must is always more forceful, more assertive than should, so use must for moral or legal obligation, rules, commands or strong advice:

You must switch off your mobile phone in the cinema – debes apagar tu móvil en el cine

You must respect your teachers – debes respetar a tus profesores

and use should for convenience or less strong advice:

You shouldn’t eat so many cakes – no deberías comer tantos pasteles.

Although not so frequently used as should, especially in negative sentences, ought to is synonymous with should with the meaning of ‘deber’:

You ought to give up smoking – deberías dejar de fumar

You ought to get up earlier – deberías levantarte más temprano

Practice -3

Complete with should or must as required

a.- You’re getting a pot belly; you ................ drink so much beer.

b.- There’s a school nearby, you ................ drive more slowly.

c.- He’s losing too much blood, we ............... call an ambulance at once.

d.- You work too hard, I think you ........................ slow down.

KEY 3

a.- shouldn’t; b.- must; c.- must; d.- should.

4.- MUST IN THE PAST

In indirect speech you can use must or had to, but only had to in direct speech:

The boss told me that I must /had to get to work earlier - el jefe me dijo que debía/tenía que llegar más temprano al trabajo.

He had to sell his house - tuvo que vender su casa.

Practice-4

Turn the following sentences into the past

a.- My father always tells me that I must obey the law.

b.- My husband is away, so I must walk the dog.

c.- He must retire at 55 owing to bad health.

d.- The cleaning lady is ill, so I must make the beds.

KEY 4

a.- My father always told me that I must/had to obey the law. b.- My husband was away, so I had to walk the dog. c.- He had to retire at 55 owing to bad health. d.- The cleaning lady was ill, so I had to make the beds.

5.- ABSENCE OF OBLIGATION/PROHIBITION

We all know that mustn’t is used to express prohibition, and needn’t or not have to for absence of obligation:

You mustn’t do it - debes hacerlo

You needn’t do it/you don’t have to do it - no tienes por qué hacerlo

But, attention, if there was no need for you to do sth, but you did it nevertheless, needn’t have is used:

You needn’t have done it – no tenías que haberlo hecho 

and if there was sth that you had to do, but you didn’t do it, use should have and not must have, because must have indicates supposition:

You should have done it – deberías haberlo hecho

Practice- 5

* Insert  needn’t or mustn’t according to whether the sentences express obligation or absence of obligation

a.- You ..................... cut the roses in the park; it’s forbidden.

b.- You ..................... tell him, I’ve already done it.

c.- You...................... wake me up; I’ve bought an alarm clock.

d.- You ..................... smoke in the office.

e.- Why did you order chicken as well? you ................... have ordered so much food

** Complete now with must have or should have according to whether you want to express supposition or sth that had to be done and wasn’t done

a.- “He didn’t phone me.” “He ........................ forgotten.

b.- “Sorry I dropped the glass”. “You ..................... been more careful.

c.- “A burglar entered my house last week”. “You .................... left the door open; you .......................... locked it.”

KEY 5

* a.- mustn’t; b.- needn’t; c.- needn’t; d.- mustn’t; e.- needn’t.

** a.- must have; b.- should have; c.- must have; should have.

6.- SHALL OR WILL FOR QUESTIONS?

· Use shall for questions that suggest sth, or ask for instructions or for the hearer’s agreement about sth.

shall we dance? - ¿bailamos?

shall I walk the dog? - ¿saco a pasear al perro?

shall I call a taxi? - ¿llamo un taxi?

· Use will for polite requests or invitations:

will you please help me? - ¿quiere ayudarme, por favor?

will you have another drink? - ¿quieres tomar otra copa?

Practice-6

Complete the following questions with shall or will as required

a.- .................. I make some coffee?

b.- .................. you pass me the salt please?

c.- .................. we play cards?

d.- .................. you join me for lunch?

KEY 6

a- shall; b- will; c- shall; d- will

7.- USED TO/TO BE USED TO

To be used to + infinitive is used to express habitual actions in the past:

I used to smoke, but I gave it up two years ago – yo solía fumar, pero lo dejé hace dos años.

to be used to + -ing form is used to express sth you are accustomed to doing:

I’m not used to getting up so early – no estoy acostumbrado a levantarme tan temprano.

Attention! for habitual actions in the present the simple present is used:

I usually get up at seven o’clock every day - Me suelo levantar a las siete todos los días

Carol is usually late - Carol suele llegar tarde.

Practice-7

Put the verb in brackets in the infinitive or the –ing form as required

a.- Basil’s used to (work) .............................................. eight hours on his farm.

b.- He’s used to (sleep) .................................. late on Sunday mornings.

c.- I used to (play) ........................................ basketball at school.

d.- Grace used to (cry) ................................... a lot when she was a baby.

e.- I’m not used to (eat) ........................................ so much.

f.- My father used to (travel) ......................................... a lot.

 KEY 7

a- working; b- sleeping; c- play; d- cry; e- eating; f- travel

8.- POLITE REQUESTS

You can make a polite request in English with the following modals: can/could, may/might and will/would.

May is more formal than can, and the past forms (could, might and would) are considered to be more polite than the present ones (can, may and will):

Can I have some coffee, please? - ¿puedo tomar café, por favor?

Could you lend me a pen, please? - ¿podrías prestarme una pluma, por favor?

May I come in? - ¿puedo pasar?

Might I have another drink? - ¿podría tomarme otra copa?

Will you please answer the phone? - ¿quieres contestar el teléfono?

Would you please stop the car? - ¿Querría usted parar el coche, por favor?

Practice-8

Make polite requests using the words in brackets

a.- ¿Quieres abrir la ventana, por favor? (will)

a.- .........................................................

b.- ¿Puedo tomar otro café? (may)

b.- ....................................................

c.- ¿Puedes ayudarme a llevar la maleta al piso de arriba? (can)

c.- ....................................................

d.- ¿Podrías prestarme tu moto? (could)

d.- ..............................................................

e.- ¿Podría traer otro amigo a la fiesta? (might)

e.- ..................................................................

KEY 8

a- will you please open the window?

b- may I have another coffee?

c- can you help me (to) carry the suitcase upstairs?

d- could you lend me your bike/motorcycle?

 e- might I bring another friend to the party?

9.- MODAL VERBS AND THE PASSIVE

Having no past participle, modal verbs cannot be conjugated in the passive, but they can express passive ideas if they are followed by a passive infinitive:

It can’t be done – no puede hacerse.

It must be done - debe hacerse.

Practice -9

Turn the following sentences into the passive

a.- You must finish this as soon as possible

a.- This ........................................................

b.- We must tell the police at once

b.- The police ................................................

c.- They might have run you over

c.- You ......................................................

d.- They ought to give him a medal

d.- He ..........................................................

KEY 9 

a- This must be finished as soon as possible

b- The police must be told once

c- You might have been run over

d- He ought to be given a medal

For a complete study of modals and semi-modals, their forms, characteristics and meanings, see my Gramática Inglesa, 9ª ed., Pearson, pp. 294-327.